Miscellaneous access technologies and standards exist currently, for example, 3rd Generation Partnership Project (3GPP)/3GPP2-based 2G and 3G, Institute of Electrical and Electronic Engineering (IEEE) 802-based Wireless Local Area Network (WLAN), Wireless Metropolitan Area Network (WMAN), and Wireless Personal Area Network (WPAN). Integration of networks is a megatrend. However, no uniform standard is available for integration and interworking between access technologies. For example, with respect to interworking with the WLAN, the 3GPP works out an interworking WLAN (I-WLAN) solution which provides loose coupling between the WLAN and the 3GPP, and a Unlicensed Mobile Access (UMA) solution which provides close coupling, both solutions requiring support of different WLAN terminals based on the corresponding standard.
(1) I-WLAN: an interworking WLAN, which accesses the IP Multimedia Subsystem (IMS) or the Internet through WLAN technologies, and then accepts various services. The I-WLAN is a solution developed by the 3GPP for interworking with the WLAN with respect to loose coupling between the WLAN and 3GPP. The 3GPP defines six scenarios of the I-WLAN.
(2) UMA: a solution for close coupling between the WLAN and 3GPP. This solution is put forward by a group led by British Telecom, including operators and terminal manufacturers, and designed to address integration among the WLAN, the Bluetooth, and the cellular networks (such as Global System for Mobile Communications/General Packet Radio Services (GSM/GPRS) core network) so that the terminal devices accept various services from the traditional cellular network through unauthorized wireless access technologies such as WLAN and Bluetooth.
Evidently, for the same access technology, such as WLAN, the upper-layer application mode may differ. Application mode refers to the mode of coupling between the access layer technology and the non-access layer technology. One access-layer technology may be coupled with different non-access layer technologies to implement relevant services. For example, the aforementioned WLAN access technology currently has two application modes, namely, I-WLAN and UMA. Therefore, in a specific communication process, the terminal needs to communicate with the network based on the same application mode. In the prior art, a specific application mode is supported by a specific terminal. However, the terminal is unable to discover or select the target network based on the application mode, thus reducing the success ratio of access and causing unnecessary delay and power consumption. Moreover, one terminal supports only one application mode, and is unable to use the network of other application mode, which makes it impossible to make the most of the access resources and leads to waste of investment.